Does Life Need a Moon?

A new study by Jack Lissaeur of NASA’s Ames Research Center reports that in order for planets to support life, they don’t necessarily need a big moon to stabilize their climate. It was suggested by previous research that Earth’s axial tilt, also called obliquity, would vary a lot over a huge chunk of time if we didn’t have the Moon. This would cause wild changes on Earth’s climate. Earth’s axial tilt right now is 23.5 degrees from the vertical.

Our planet is a paradox in the Solar system, being the only celestial body that has such a big natural satellite like the Moon, circling around it. The moon’s strong gravitational pull has kept Earth in line, limiting the planet’s axial tilt between 22 and 24.6 degrees from the vertical over time. With a 0 degree tilt, our Sun would be all the time over the equator and the poles would barely get sunlight. If this tilt was let’s say 85 degrees, the poles will get a lot of sunlight. Flipping from 0 to 85 degrees would cause a dramatic change in Earth’s climate.

Lissauer and his team concluded that without a moon, this axial tilt swings would not be so violent as previously expected. They would vary a lot more than they are now on Earth, but they would be far less than expected and over a great period of time, allowing an advance life to appear (if other conditions are right).